GlueX TOF Meeting, September 23, 2020

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GlueX Time-of-Flight Meeting
Wednesday, September 23, 2020
10:00 am EDT
BlueJeans: 350 531 998


  1. Announcements
  2. Review of minutes from the last meeting
  3. TOF end-of-run report
  4. Calibration
  5. SAD Plans
  6. TOF NIM paper
  7. Action Item Recap


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2020 on the JLab CUE. This directory is accessible from the web at .


Present: Eugene Chudakov, Mark Ito (chair), Sasha Ostrovidov, Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials to gain access.

Review of minutes from the last meeting

We went over the minutes from September 9th, hot off the presses. We mainly discussed repairs to the TOF during the SAD.

  • Sasha mentioned that he thought if there is broken light guide on at the top of the array, it might be able to be repaired without dismounting the entire array.
  • Beni told us is the next step is for him to do a comprehensive review of counter performance and identify candidates for PMT replacement or light guide repair.
  • We agreed we should contact Paul Eugenio and discuss the idea of getting him up hear to effect/supervise repairs. Such a plan is hugely complicated during a pandemic, clearly.


  • Beni reported that there are still a few runs from the end of the run period that need calibration.
  • He also has done a re-calibration of the bulk of the runs after fixing a problem with peak finding in the distributions of the L-R time differences. He did not have to re-do the walk corrections, thus avoiding the problematic ADC reported previously.
  • There was an email discussion about the size of the TOF calibration skim. Beni needs to got through 70 files per run, which is a large fraction of the total raw data, mainly to get enough exposure for the outer counters. There was even a thought about a special trigger to help out with this requirement. Mark will forward the messages to Beni.

TOF end-of-run report

  • Beni turned off all of the detector voltages after the run had ended.
  • The electronics in the Hall are still mostly on. The decision on when to turn them off has not been made.

Upcoming Run

Beni noted that SRC and PrimEx do not have any special requirements for the TOF, but they should be aware that tracking is needed to verify the calibration. Eugene reminded us that SRC uses a normal GlueX set-up, just with a different target and that PrimEx will run without the solenoid field and will not use the tracking chambers. He also mentioned that there was some straight track running in the summer run just past.

Action Item Recap

  1. Decide on when to ship PMTs to JLab from FSU (Mark, Paul Eugenio)
  2. Prepare a complete draft of the TOF NIM paper. (all)
  3. Make a plan for TOF repair during the SAD, including Paul in the discussion. (all)
  4. Send TOF calibration skim email discussion to Beni. (Mark)